42% — Will Donald Trump endorse Donald J. Trump Jr. in the 2028 presidential election before Mar 1, 2028 Leader: J.D. Vance at 42% · Kalshi 42% · 4 contracts · $2K volume · medium confidence Updated 2026-08-10 04:41:09 UTC Tracks the leading outcome in a winner-take-all prediction market set with 4 outcomes. Why this matters: This market estimates the likelihood that Donald Trump will remain neutral through early March 2028, endorsing no candidate in the 2028 presidential election. The 54% probability reflects market uncertainty about Trump's strategic choices in the pre-primary period. Key drivers include Trump's historical tendency to remain flexible in endorsements, pressure from potential candidates seeking his backing, and the evolving Republican field. The market currently prices J.D. Vance as the next-most-likely endorsement target at 22%, suggesting fragmented expectations about Trump's preferred outcome. The main catalyst will be Trump's own statements and public positioning as the campaign accelerates—any explicit endorsement or clear commitment would immediately resolve this contract. The resolution date of March 1, 2028 captures the period leading into Super Tuesday, when primary outcomes begin crystallizing. Key factors: - Trump's track record of late endorsement timing and strategic flexibility in Republican primary races - The relative price gap between 'no endorsement' (54¢) and the leading alternative candidate endorsement 'Vance' (22¢), indicating material disagreement about his involvement - Whether Trump announces a 2028 campaign of his own before March 1, which would fundamentally alter his endorsement calculus - Public statements and social media activity from Trump regarding 2028 field candidates between now and early March 2028 - Historical precedent: Trump endorsed late in 2016 and 2020 cycles, suggesting baseline probability of continued non-commitment through early primary season Contracts: - Will Donald Trump endorse J.D. Vance in the 2028 presidential election before Mar 1, 2028?: J.D. Vance — 42¢ Kalshi $426 (weight 28%) - Will Donald Trump endorse Marco Rubio in the 2028 presidential election before Mar 1, 2028?: Marco Rubio — 34¢ Kalshi $856 (weight 55%) - Will Donald Trump endorse no one in the 2028 presidential election before Mar 1, 2028?: No one — 10¢ Kalshi $250 (weight 16%) - Will Donald Trump endorse Himself in the 2028 presidential election before Mar 1, 2028?: Himself — 3¢ Kalshi $17 (weight 1%) --- ## Methodology SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours. ## SF Signal - SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration. - No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only. --- *Last verified: 2026-08-10T04:20:51.318Z* By SimpleFunctions — https://simplefunctions.dev/ Cite as: "42% per prediction markets (SimpleFunctions, August 2026)" Canonical: https://simplefunctions.dev/answer/trumpendorse28 Full data: https://simplefunctions.dev/api/public/query?q=Will%20Donald%20Trump%20endorse%20Donald%20J.%20Trump%20Jr.%20in%20the%202028%20presidential%20election%20before%20Mar%201%2C%202028 Provider: SimpleFunctions — https://simplefunctions.dev